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| United States Patent |
5,506,332
|
|
Funhoff
, et al.
|
April 9, 1996
|
Preparation of polyacetals, use thereof and novel polyacetals
Abstract
A process for preparing polyacetals by copolymerization of glyoxylic esters
with other copolymerizable monomers in the presence of anionic or cationic
polymerization initiators, with or without the introduction of stable end
groups and with or without hydrolysis of the copolymerized units of
glyoxylic ester present in the copolymer comprises using as monomers
cyclic formals derived from diols, homopolymers of formaldehyde,
trioxepane or mixtures thereof, although up to 50% by weight of this group
of monomers may be replaced by other customary copolymerizable monomers,
and the poly(acetal-carboxylate)s thus obtainable are useful as additives
in reduced-phosphate and phosphate-free detergents and cleaners, as water
treatment agents and as dispersants for finely divided substances.
| Inventors:
|
Funhoff; Angelika (Heidelberg, DE);
McKee; Graham E. (Weinheim, DE);
Hartmann; Heinrich (Limburgerhof, DE);
Baur; Richard (Mutterstadt, DE);
Kud; Alexander (Eppelsheim, DE);
Schwendemann; Volker (Neustadt, DE)
|
| Assignee:
|
BASF Aktiengesellschaft (Ludwigshafen, DE)
|
| Appl. No.:
|
374527 |
| Filed:
|
February 2, 1995 |
| PCT Filed:
|
August 16, 1993
|
| PCT NO:
|
PCT/EP93/02176
|
| 371 Date:
|
February 2, 1995
|
| 102(e) Date:
|
February 2, 1995
|
| PCT PUB.NO.:
|
WO94/04585 |
| PCT PUB. Date:
|
March 3, 1994 |
Foreign Application Priority Data
| Aug 25, 1992[DE] | 42 28 159.8 |
| Current U.S. Class: |
528/232; 508/221; 508/223; 508/497; 510/476; 510/533; 524/773; 524/843; 525/472; 528/230; 528/243; 528/248; 528/250 |
| Intern'l Class: |
C08G 004/00 |
| Field of Search: |
528/230,232,243,248,250
525/472
524/773,843
252/32,32.5,174.23
|
References Cited
U.S. Patent Documents
| 4169934 | Oct., 1979 | Papanu.
| |
| Foreign Patent Documents |
| 0001004B1 | Aug., 1978 | EP.
| |
Other References
Houben-Weyl, vol. E30, Part 2, Georg Thieme Verlag, p. 1393 (1987).
|
Primary Examiner: Acquah; Samuel A.
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier & Neustadt
Claims
We claim:
1. A process for preparing polyacetals optionally having stable end groups
by:
copolymerizing (a) glyoxylic esters with (b) other copolymerizable
monomers, at least 50% of which monomers (b) are cyclic formals derived
from diols, homopolymers of formaldehyde, trioxepane or mixtures thereof
in the presence of anionic or cationic polymerization initiators, the
glyoxylic ester monomer units optionally being hydrolyzed.
2. The process of claim 1, wherein said glyoxylic esters are selected from
the group consisting of methyl glyoxylate, ethyl glyoxylate, n-propyl
glyoxylate, isopropyl glyoxylate, n-butyl glyoxylate, isobutyl glyoxylate,
stearyl glyoxylate and palmityl glyoxylate.
3. The process of claim 1, wherein the ratio of glyoxylic ester monomer to
monomers (b) ranges from 1-99:99-1, on a weight % basis.
4. The process of claim 3, wherein said ratio ranges from 50-95:5-50.
5. The process of claim 1, wherein at least 50% of said monomers (b) are
dioxolane, butanediol formal, trioxane or combinations thereof.
6. The process of claim 1, wherein up to 50% by weight of said monomers (b)
are (c) epoxides, aldehydes having at least 2 carbon atoms,
tetrahydrofuran,. C.sub.2-4 olefins or combinations thereof.
7. The process of any one of claims 1-6, wherein the ends of the polyacetal
chains are tipped with chemically stable groups which confer stability to
the polyacetals against degradation at alkaline pH.
8. Polyacetals prepared by the process of claim 1.
Description
RELATED APPLICATIONS
This application was filed as PCT International Application Number PCT/EP
93/02176 on Aug. 16, 1993.
The present invention relates to a process for preparing polyacetals by
copolymerizing glyoxylic esters with other copolymerizable monomers in the
presence of anionic or cationic polymerization initiators and optional
hydrolysis of the copolymerized units of glyoxylic ester present in the
copolymer, to the use of the copolymers thus obtainable as additive in
detergents and cleaners, as water treatment agent, and as dispersant for
finely divided substances, and to novel polyacetals.
EP-B-0 001 004 discloses polymeric acetalcarboxylates of the formula
##STR1##
where Y is at least one comonomer which is present in the polymer in
random distribution,
p is from 0 to 2,
q is at least 1,
R.sup.1 and R.sup.2 are chemically stable groups which stabilize the
polymers against degradation at an alkaline pH,
n is from 10 to 200, and
M is an alkali metal, ammonium, C.sub.1 -C.sub.4 -alkyl or an alkanolamine
having from 1 to 4 carbon atoms.
The poly(acetal-carboxylate)s are prepared by homopolymerization of
glyoxylic esters or by copolymerization of glyoxylic esters with
copolymerizable compounds, such as epoxides, aldehydes,
carboxyl-containing compounds and mixtures thereof in the presence of
cationic catalysts, such as boron trifluoride etherates, or anionic
initiators, such as sodium methyl diethylmalonate. To stabilize the
polyacetals thus obtainable against degradation at an alkaline pH, the
ends of the polymer chains are tipped with chemically stable groups; for
example, the substituents R.sup.1 and R.sup.2 in the formula I can each be
alkyl, hydroxyalkyl or carboxymethyl. The poly(acetal-carboxylate)s of the
formula I are used as builders in detergents and cleaners. The
poly(acetal-carboxylate)s are biodegradable.
U.S. Pat. No. 4,169,934 discloses copolymers of the general formula
##STR2##
where p is at least 1, n is at least 2, Y is at least one monomer from the
group of the olefins and the aldehydes having from 1 to 3 carbon atoms,
and M is as defined in the formula I.
According to Example 1 of the cited patent, dimethyl ketomalonate is
dissolved in methylene chloride and copolymerized with formaldehyde at
about 0.degree. C. using sodium diethyl methylmalonate as initiator. After
the copolymerization trifluoroacetic acid and ethyl vinyl ether are added
to the mixture and the ester groups of the copolymer are hydrolyzed with
aqueous sodium hydroxide solution. The sodium salts of the copolymers thus
obtainable are used as builders in detergents. The copolymers are stable
under alkaline conditions, but depolymerize in an acid medium to form
biodegradable fragments. In the process described in U.S. Pat. No.
4,169,934 the formaldehyde is introduced into the polymerizing mixture in
gas form. The use of liquid formaldehyde as comonomer appears to be
possible in principle, but is out of the question in industry because of
the tendency of anhydrous formaldehyde to undergo explosive
polymerization. According to the reaction scheme indicated in Houben-Weyl,
Volume E30, Part 2, Georg Thieme Verlag, page 1393 (1987), anhydrous
formaldehyde can be polymerized not only cationically but also
anionically.
It is an object of the present invention to provide an improved process for
preparing polyacetals by copolymerization of glyoxylic esters with
formaldehyde and optionally with other copolymerizable monomers. It is a
further object of the present invention to devise detergent additives,
water treatment agents and dispersants for solid substances. It is yet a
further object of the present invention to provide novel substances.
We have found that the first object is achieved by a process for preparing
polyacetals by copolymerization of
(a) glyoxylic esters with
(b) other copolymerizable monomers in the presence of anionic or cationic
polymerization initiators, with or without the introduction of stable end
groups and with or without hydrolysis of the copolymerized units of
monomer (a) present in the copolymer, which comprises using as monomers
(b) cyclic formals derived from diols, homopolymers of formaldehyde,
trioxepane or mixtures thereof, although up to 50% by weight of this group
of monomers (c) may be replaced by other customary copolymerizable
monomers.
We have found that the second object is achieved by using the polyacetals
obtainable by the novel process as additive in reduced-phosphate and
phosphate-free detergents and cleaners, as water treatment agent and as
dispersant for finely divided substances.
We have found that the last object is achieved by polyacetals obtainable by
anionically or cationically initiated polymerization of
(a) glyoxylic esters with
(b) cyclic formals derived from diols, with the exception of those cyclic
formals which are derived from 1,2-diols, although if desired up to 50% by
weight of this group of monomers may be replaced by other customary
copolymerizable monomers, with or without the introduction of stable end
groups and with or without hydrolysis of the ester groups of the
copolymerized units of monomer (a) present in the copolymers.
Suitable for use as component (a) are glyoxylic esters which are obtainable
for example by esterifying glyoxylic acid with C.sub.1 -C.sub.20
-alcohols, eg. methyl glyoxylate, ethyl glyoxylate, n-propyl glyoxylate,
isopropyl glyoxylate, n-butyl glyoxylate, isobutyl glyoxylate, stearyl
glyoxylate and palmityl glyoxylate. The use of methyl glyoxylate and ethyl
glyoxylate is particularly preferred. The compounds of component (a) are
polymerized in a virtually anhydrous form. If the aldehyde group of the
ester is in the form of a hemiacetal, the alcohol moiety should be
eliminated, for example by treatment with phosphorus pentoxide, and the
resulting aldehyde purified by distillation.
Suitable monomers for use as component (b) according to the invention are
cyclic formals derived from diols. These cyclic formals are obtainable by
reacting diols with formaldehyde. For instance, dioxolane is obtained by
reacting ethylene glycol with formaldehyde. Further suitable cyclic
formals are 1,3-propanediol formal, 1,2-propanediol formal, 1,4-butanediol
formal, 1,3,6-trioxocane (reaction product of diethylene glycol and
formaldehyde) and 1,5-pentanediol formal.
Also suitable for use as component (b) are homopolymers of formaldehyde,
eg. trioxane and other cyclic oligomers of formaldehyde, eg.
1,3,5,7-tetraoxocane, and also polyformaldehyde. The group of monomers
suitable for use as component (b) also includes trioxepane, which can be
prepared by reacting dioxolane and formaldehyde under acid catalysis. In
the copolymerization the compounds of group (b) can be used alone or as a
mixture of 2 or more components of this group.
The monomers of group (a) can be copolymerized with the monomers of group
(b) in any desired ratio. For example, the copolymerization may be carried
out with the monomers (a) in an amount of from 1 to 99, preferably from 50
to 95, % by weight and the monomers (b) in an amount of from 99 to 1,
preferably from 5 to 50, % by weight. The monomers of group (b) may if
desired be replaced to an extent of up to 50% by weight by other customary
monomers copolymerizable with the monomers (a), these other monomers being
hereinafter referred to as monomers (c). Suitable monomers (c) are
mentioned for example in previously cited EP-B-0 001 004. These comonomers
are epoxides, aldehydes having at least 2 carbon atoms, tetrahydrofuran
and/or C.sub.2 -C.sub.4 -olefins. Specific examples are ethylene oxide,
propylene oxide, butylene oxide, styrene oxide, ethylene, propylene,
isobutene, tetrahydrofuran, glycidyl compounds, cyclohexene oxide,
epoxidized fatty acid esters, eg. glycidyl acrylate and glycidyl
methacrylate, glycidol, acetaldehyde, n-propionaldehyde, n-butyraldehyde,
isobutyraldehyde, n-pentanal, n-hexanal, acrolein, methacrolein,
crotonaldehyde, including isomer mixtures; hydroxypivalaldehyde and also
crosslinking aldehydes such as glyoxal.
Suitable polymerization initiators are anionic or cationic initiators which
are likewise mentioned in previously cited EP-B-0 001 004. Examples of
suitable anionic polymerization initiators are the sodium derivatives of
diethyl malonate, diethyl methylmalonate or dimethyl methylmalonate. The
sodium derivatives of these esters are prepared for example by reacting
the esters with sodium hydride. Other suitable anionic polymerization
initiators are amines, such as triethylamine,
1,4-diazabicyclo[2,2,2]octane, pyrrocoline and quinolizidine,
alkanolamines such as triethanolamine, alkali metal bases such as sodium
hydroxide, potassium hydroxide and lithium hydroxide and also alkaline
earth metal bases, for example calcium hydroxide, calcium oxide, barium
hydroxide and barium oxide, or mixtures thereof, or alkaline earth metal
hydrides such as calcium hydride.
Examples of suitable cationic initiators are boron trifluoride etherates,
eg. the complex of boron trifluoride and diethyl ether or complexes of
boron trifluoride and phenol. Also, BF.sub.3 alone can be used as
polymerization initiator. However, it is also possible to use mixtures of
multiple cationic or of multiple anionic initiators. The amount of
initiator is in each case from 5 to 500 ppm, based on the monomers used.
However, the catalysts can also be used in concentrations of up to about
1% by weight or higher.
The copolymerization is preferably carried out in an inert organic solvent,
eg. acetonitrile, methylene chloride, pentane, hexane, cyclohexane,
toluene, dioxane, diethylene glycol dimethyl ether, ethylene glycol
dimethyl ether, propionitrile, benzonitrile and i-butyronitrile. It is
also possible to use mixtures of 2 or more solvents or to carry out the
copolymerization in the absence of solvents.
The copolymerization temperature is within the range from -20.degree. to
100.degree. C., preferably from 0.degree. to 70.degree. C. After the
polymerization has ended, the ends of the polymer chains are capped with
chemically stable groups by adding to the polyacetals groups which are
stable to degradation at an alkaline pH. Groups of this kind are for
example alkyl groups such as methyl, ethyl, propyl and butyl groups and
others such as decyl, dodecyl and cycloalkyl groups; alkenes such as
ethylene, propylene, butylene and higher olefins, also branched
hydrocarbons such as 2-methylbutane or aromatic hydrocarbons such as
toluene, xylene and cyclic hydrocarbons such as cyclohexane and
cyclohexene; alcohols such as methanol, ethanol, glycol, butanediol;
mercaptans such as methanethiol, 1,2-ethanedithiol; ethers such as
dimethoxymethylene, also carboxyl containing compounds such as substituted
malonic esters or salts and anhydrides such as acetic anhydride.
To introduce the stable end groups, the reaction mixture is admixed for
example with the following compounds which add to the ends of the polymer
chains: vinyl ethers such as vinyl ethyl ether, dihydropyrans, alkylating
agents such as dimethyl sulfate, methyl iodide, ethers such as
dimethoxymethylene, epichlorohydrin, epoxysuccinic esters and/or
epoxybutyric esters.
Stabilization through addition of specific groups to the polyacetals is not
absolutely necessary and is carried out only in those cases where the
polyacetals have to meet enhanced stability requirements in the alkaline
pH range. In the anionically initiated polymerization, stabilizing end
groups are preferably always introduced into the polymers. The copolymers
can be isolated directly from the reaction mixture or else be subjected to
a hydrolysis. To this end the copolymers are treated in an aqueous medium
with bases, for example alkali metal bases such as sodium hydroxide
solution, potassium hydroxide solution, sodium carbonate or potassium
carbonate, with alkaline earth metal bases, such as calcium hydroxide or
barium hydroxide, or with ammonia and amines such as triethanolamine,
ethanolamine or triethylamine, or mixtures thereof. This then gives the
salts of the copolymers, of which in particular the alkali metal and
ammonium salts are of significance for practical use. The salts can be
used to prepare polyacetals which contain free carboxyl groups.
The hydrolyzed copolymers are used as additive in reduced-phosphate and
phosphate-free detergents and cleaners. Reduced-phosphate detergents are
for the purposes of the present invention detergents whose phosphate
content is less than 25% by weight, calculated as sodium triphosphate. The
compositions of detergent and cleaner formulations can differ greatly.
Detergent and cleaner formulations customarily contain from 2 to 50% by
weight of surfactants with or without builders. These figures apply both
to liquid and to pulverulent detergent and cleaner formulations. Examples
of the compositions of detergent formulations which are customary in
Europe, the USA and Japan can be found in table form for example in
Chemical and Eng. News 67 (1989) , 35. Further details concerning the
compositions of detergents and cleaners can be found in WO-A-90/13581 and
in Ullmanns Encyklopadie der technischen Chemie, Verlag Chemie, Weinheim
1983, 4th Edition, pages 63-160. Also of interest are those detergent
formulations which contain up to 60% by weight of alkali metal silicate
and up to 10% by weight of a polyacetal prepared according to the present
invention.
The detergents may additionally contain a bleaching agent, for example
sodium perborate, which if used can be present in the detergent
formulation in an amount of up to 30% by weight. Detergents and cleaners
may additionally contain further customary additives, for example
complexing agents, opacifiers, optical brighteners, enzymes, perfume oils,
color transfer inhibitors, grayness inhibitors and/or bleach activators.
The polyacetals are used in detergents in amounts from 0.5 to 20,
preferably from 2 to 10, % by weight.
The hydrolyzed and neutralized polyacetals are also used as water treatment
agents. They are effective in preventing the formation of troublesome
deposits in water-conveying plant, such as coolers, boilers and
evaporators. An example of a use of this kind is in evaporation plant for
sea water desalination. Based on water, the polyacetals are used in
amounts of from 1 to 1000, preferably from 2 to 100, ppm.
The hydrolyzed and neutralized polyacetals are also suitable for use as
dispersants for finely divided substances, eg. clays, chalk, calcium
carbonate, titanium dioxide, iron oxides, kaolins, aluminum oxide, cement
and oxidic glazes for ceramic purposes.
If used as dispersants, it is customarily necessary to employ from 0.02 to
1% by weight, based on the finely divided substances.
Anionic copolymerization of
(a) glyoxylic esters with
(b) cyclic formals derived from diols or cyclic polymers of formaldehyde
and optional hydrolysis of the ester groups of the copolymerized units of
monomer (a) present in the copolymers results in carboxylato- or
carboxyl-containing polyacetals. The formation of polyacetals of this kind
was unforeseeable, since it is known from Houben-Weyl, Volume E30, Part 2,
Georg Thieme Verlag, page 1396 (1987), that for example 1,3,5-trioxane and
other cyclic oligomers of formaldehyde can be polymerized only with a
cationic initiator. The results of anionically copolymerizing methyl
glyoxylate with dioxolane are, for example, polyacetals which contain the
following structural units:
##STR3##
The preferred monomers of group (b) for preparing these polyacetals are
dioxolane, butanediol formal and/or 1,3,5-trioxane. The polyacetals
obtained by anionic polymerization of glyoxylic esters with cyclic formals
or cyclic polymers of formaldehyde are novel substances. They have a lower
residual monomer content and higher molecular weights than the glyoxylic
esters obtainable using formaldehyde as the monomer of component (b). The
copolymers obtainable by the process of the invention have K values
(determined by the method of H. Fikentscher on a 1% strength by weight
aqueous solution of the sodium salt at pH 7 and 25.degree. C.) of from 8
to 100, preferably of from 10 to 80.
In the examples the percentages are by weight. The K values were determined
by the method of H. Fikentscher, Cellulose-Chemie 13 (1932), 58-64, 71-74,
on 1% strength by weight aqueous solutions of the sodium salts of the
polyacetals at 25.degree. C. and pH 7.
EXAMPLE 1
A 100 ml capacity single neck flask equipped with a magnetic stirrer and a
device for working under inert gas was charged under argon with 4.5 ml of
acetonitrile, 15.9 g (181 mmol) of freshly distilled methyl glyoxylate and
1.8 g (24 mmol) of dioxolane. To this mixture was added 14 .mu.l (0.027
mmol) of sodium diethyl methylmalonate in a single portion. An exothermic
reaction occurred. By cooling the reaction mixture with an ice bath the
reaction temperature was kept at below 10.degree. C. The reaction mixture
was subsequently polymerized at from 3.degree. to 7.degree. C. for 1.5
hours. The polymer solution was then admixed at 0.degree. C. with 4.6 g
(59 mmol) of dimethoxymethane and 4.4 g (31 mmol) of phosphorus pentoxide
and thereafter with a further 4.6 g of dimethoxymethane. Following a
reaction time of 3 hours 60 ml of 2 N sodium hydroxide solution were added
to the reaction mixture, which was stirred and decanted. The copolymer was
washed three times with 30 ml of saturated aqueous sodium bicarbonate
solution each time and saponified with 25 ml of 10 N sodium hydroxide
solution. The copolymer was precipitated from 1:1 v/v methanol/acetone.
The yield was 90%, based on the sodium salt of the copolymer. The
hydrolyzed product had a K value of 31.
EXAMPLE 2
The apparatus described in Example 1 was charged with 14.1 g (160 mmol) of
methyl glyoxylate, 3.5 g (39 mmol) of trioxane and 4.5 ml of acetonitrile.
Then 14 .mu.l (0.027 mmol) of sodium diethyl methylmalonate were added.
The reaction mixture began to heat up. The flask was placed in an ice bath
and the reaction mixture was stirred for 1.5 hours. In succession, 4.6 g
(59 mmol) of dimethoxymethane, 4.4 g (31 mmol) of phosphorus pentoxide and
a further 4.6 g (59 mmol) of dimethoxymethane were added at an internal
temperature of 0.degree. C. Thereafter the reaction mixture was stirred
for a further 3 hours. The copolymer was then washed with 60 ml of 2 N
sodium hydroxide solution and stirred up, and the supernatant was decanted
off. The copolymer was then washed three times with 30 ml of a saturated
aqueous sodium bicarbonate solution and hydrolyzed and neutralized with 25
ml of 10 N sodium hydroxide solution. The copolymer was precipitated from
1:1 v/v methanol/acetone. The yield of sodium salt of the copolymer was
quantitative. The K value of the copolymer was 29.
EXAMPLE 3
The apparatus described in Example 1 was charged with 8.8 g (100 mmol) of
methyl glyoxylate, 8.8 g (119 mmol) of dioxolane and 4.5 ml of
acetonitrile, and the initial charge was admixed with 14 .mu.l (0.027
mmol) of sodium diethyl methylmalonate. The reaction mixture was then
cooled down to 0.degree. C. and stirred at that temperature for 1.5 hours.
The resulting viscous mass was then admixed with 4.6 g (59 mmol) of
dimethoxymethane, 4.4 g (31 mmol) of phosphorus pentoxide and 4.6 g (59
mmol) of dimethoxymethane and stirred at 0.degree. C. for 3 hours. Then 60
ml of 2 N sodium hydroxide solution were added, the mixture was stirred,
and the aqueous solution was decanted off. The copolymer left behind was
washed three times with 30 ml of saturated aqueous sodium bicarbonate
solution each time and then hydrolyzed and neutralized with 12 ml of 10 N
sodium hydroxide solution. The product was precipitated from 1:1 v/v
methanol/acetone. The yield of hydrolyzed and neutralized copolymer was
44%. The copolymer had a K value of 30.
COMPARATIVE EXAMPLE 1
The apparatus described in Example 1 was charged with 15 ml of
dichloromethane and 35.2 g (400 mmol) of methyl glyoxylate, and the
initial charge was cooled down to about 5.degree. C. 1 ml of 0.05M sodium
diethyl methylmalonate solution was then added. 10 g (333 mmol) of gaseous
formaldehyde were then passed into the resulting mixture. A slow
exothermic reaction occurred. After about 45 minutes 22 ml of
dimethoxymethane and 8.8 g (62 mmol) of phosphorus pentoxide were added
with ice bath cooling and the mixture was stirred at 5.degree. C. for 3
hours. The copolymer was then washed first with 120 ml of 2 N sodium
hydroxide solution and then three times with 60 ml of saturated aqueous
sodium bicarbonate solution each time and thereafter saponified with 25 ml
of 10 N sodium hydroxide solution. The polymer was precipitated from 1/1
acetone/methanol. The yield of sodium salt of the copolymer was 23 %. The
hydrolyzed product had a K value of 8.
COMPARATIVE EXAMPLE 2 (ANALOGOUSLY TO EXAMPLE 1 OF U.S. PAT. NO. 4,169,934)
The apparatus described in Example 1 was charged with 4 ml of
dichloromethane and 17.4 g (0.1M) of diethyl ketomalonate, and the initial
charge was cooled down to 0.degree. C. Then 0.5 ml of a 0.05M sodium
diethyl methylmalonate solution was added and gaseous formaldehyde was
passed into the reaction mixture, at which point the polymerization
started. The reaction mixture was stirred in an ice bath. After about 45
minutes the temperature of the reaction mixture had come back down to
0.degree.-2.degree. C. and 0.18 ml (1.5 mol %) of trifluoroacetic acid and
3.5 ml of ethyl vinyl ether were added to the mixture. The mixture was
stirred at room temperature overnight and then admixed with approximately
2 ml of 1 N sodium hydroxide solution, and the volatiles were removed
under reduced pressure. Then 12 ml of 5 N sodium hydroxide solution were
added and the reaction mixture was stirred at 0.degree. C. for 2 hours. It
was then warmed to room temperature. The precipitate which had formed on
addition of the 5 N sodium hydroxide solution was filtered off and dried.
It was then dissolved in distilled water, precipitated from methanol and
filtered off. The yield was 80%, and the K value was 9.5.
COMPARATIVE EXAMPLE 3
The apparatus described in Example 1 was charged with 4.5 ml of
dichloromethane and 17.6 g (200 mmol) of methyl glyoxylate, and the
initial charge was cooled down to 0.degree. C. Then 13.9 .mu.l of diethyl
methylmalonate were added, which started an exothermic reaction. The
reaction mixture was subsequently stirred in an ice bath for a further 1.5
hours, and then at 0.degree. C. admixed with 4.6 g (59.3 mmol) of
dimethoxymethane and 4.4 g (31 mmol) of phosphorus pentoxide. Thereafter a
further 4.6 g (59.3 mmol) of dimethoxymethane were added. The mixture was
subsequently stirred at that temperature for 3 hours, then washed with 60
ml of 2 N sodium hydroxide solution and three times with 30 ml of
saturated sodium bicarbonate solution each time and saponified with 25 ml
of 10 N sodium hydroxide solution. The polymer was precipitated from 1:1
methanol/acetone and had a K value of 43. The yield was quantitative.
The above-described copolymers and the homopolymer of Comparative Example 3
were tested as detergent additive. For this they were incorporated at 5%
by weight in a detergent A of the following composition:
______________________________________
Detergent A
Parts by weight
______________________________________
Sodium dodecylbenzenesulfonate
6.25
C.sub.13 /C.sub.15 oxo alcohol alkoxylated with
4.70
ethylene oxide in a molar ratio of 1:7
Magnesium silicate 1.25
Sodium carbonate (anhydrous)
10.00
Sodium metasilicate .times. 5 H.sub.2 O
6.00
Sodium perborate tetrahydrate
20.00
Sodium sulfate (anhydrous)
6.75
Soap 2.80
Sodium carboxymethylcellulose
0.60
Zeolite A 30.00
Polymer 5.00
Water remainder to 100.00
______________________________________
The detergent formulation A was used to wash test cloths in woven cotton.
The number of wash cycles was 15. After this number of washes the ash
content of the cloth was determined by ashing each cloth at 700.degree. C.
for 2 hours.
The effect (W) of additives in this detergent A is reported in percent
effectiveness on a scale where 0% effect corresponds to the ash content
without incrustation inhibitor (A-without) (ie. without added copolymer)
and 100% corresponds to the ash content of the cloth prior to washing
(A-zero). The effect is then calculated from the ash content assuming a
linear response.
##EQU1##
The pre-wash ash content of the pure cotton cloth was 0.04%. The maximum
ash content without inhibitor (A-without) was 6.91%. The ash content is
denoted by A when the polymer is used.
Experimental conditions for determining the incrustation
Apparatus: Launder-O-meter from Atlas, Chicago
Number of wash cycles: 15
Wash liquor: 250 g, the water used containing 4 mmol of hardness per liter
(molar ratio of calcium to magnesium equal to 4:1)
Washing time: 30 min at 60.degree. C. (including heating-up time)
Detergent dosage: 7 g/l
Liquor ratio: 12.5:1
Test fabric: 20 g each
The absolute effect in % on using the polymers prepared in the Examples and
Comparative Examples is indicated in the following table:
TABLE
______________________________________
Polymer prepared in % effect of
Comparative
polymer in
Example Example detergent A
______________________________________
1 -- 47.8
2 -- 60.4
3 -- 38.9
-- 1 10.0
-- 2 0
-- 3 52.1
without polymer
4 0
______________________________________
As the Examples and Comparative Examples show, the incrustation-inhibiting
effect of the copolymers of glyoxylic esters and cyclic ethers is similar
to that of the homopolymers of glyoxylic esters. This is surprising
because it had to be expected that the incorporation of comonomers that do
not carry carboxyl groups would result in a reduced
incrustation-inhibiting performance.
A considerable advantage of the copolymers is their better biodegradability
compared with the polyglyoxylates.
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